CN1603233A

CN1603233A - Process for producing ammonia with ultra-low metals content

Info

Publication number: CN1603233A
Application number: CNA2004100833030A
Authority: CN
Inventors: 丹尼尔·J·德肖维茨; 瑞安·L·米尔斯; 杰伊·F·施奈特; 柯蒂斯·多弗; 萨丹纳·马哈潘特拉; 凯文·K·沃滋沃斯
Original assignee: Ashland Inc
Current assignee: Ashland Inc
Priority date: 2000-12-27
Filing date: 2001-11-27
Publication date: 2005-04-06
Also published as: ZA200304870B; DE60104023D1; EP1353877B1; US20020081259A1; KR20030083689A; AU2002217856A1; US20030108473A1; CN1483000A; WO2002051752A3; JP2004521055A; DE60104023T2; WO2002051752A2; ATE269836T1; US6534027B2; EP1353877A2

Abstract

Commercial grade ammonia is purified for use in production of semiconductors by initially passing the liquid ammonia through a liquid phase oil separation system. This removes the vast majority of the impurities. The filtered liquid ammonia is then passed through a vaporizer which quiescently forms ammonia vapor and prevents entrainment of impurities within the ammonia vapor. The vapor passes through a vapor filtration system and subsequently to a bubble column. The bubble column is designed so that the bubbles are small enough and travel at a rate which ensures that any entrapped particle within the bubble will have time to migrate to the surface of the bubble and thereby pass through the liquid phase. The collected vapor is directed through subsequent vapor filters and is collected. If anhydrous ammonia is desired, the ammonia vapor is collected upstream of the bubble column.

Description

Make the method for the ammonia of ultra-low metals content

The denomination of invention that the application submitted for November 27 calendar year 2001 is divided an application for No. the 01821474.6th, the Chinese patent application of " making the method for the ammonia of ultra-low metals content ".

Technical field

The ammonium hydroxide of ultra-high purity is generally used for making semiconductor product such as microprocessor.Particularly it is used as cleaning solution in making unicircuit.Because these circuit become more and more littler, impurity becomes and more is difficult to stand.Especially, used ammonium hydroxide must not have any conductive contaminants, especially metal pollutant.Unicircuit also has demand for the superfine gaseous ammonia of high purity.

Background technology

Usually the commercial ammonia of making all is not suitable for this type of application.Introduced the pollutent that comprises oil and metallics such as the manufacturing of the ammonia that is used for fertilizer.This commercial grade or fertilizer grade ammonia can comprise up to 10ppm free oil and a few ppm cadmium, calcium, sodium, iron, zinc and potassium.In order to be used for the unicircuit manufacturing, these concentration of metallic impurities should be lower than about 100ppt.

Many methods have been designed with this commercial grade ammonia of purifying.Yet because a variety of causes, they are not optimised design.People's such as Hoffman United States Patent (USP) disclose for the 5th, 496, No. 778 and 5,846, No. 386 by the liquefied ammonia container obtain ammonia steam and with this steam by filtering out the particulate filtration device.Because the amount of impurity in the ammonia, in vapour phase, remove these impurity and be inefficient and macroscopic view on be invalid.The small size of many metal particles makes steam filtration inoperative.In addition, the design of vaporizer is allowed and is carried impurity secretly.

Japanese Patent 8-119626-A discloses the aqueous solution of ammonia by saturated ammonia.This allows carrying secretly in the mist, and requires mist separator subsequently.Also because Design of device does not have time enough by removing degranulation in the liquid bath.Having designed filtration procedure deoils to remove from ammonia.But these all can not make the ammonia of ultra-high purity.

Summary of the invention

Prerequisite of the present invention is to recognize, can collect liquefied ammonia by at first filtering with liquid filtration device/collector by commercial grade ammonia, obtains ultra-pure ammonia with the metallic particles of removing nearly all oil and being carried by oil.The clean ammonia liquid of this part imports the immobilized vaporizer subsequently, and it promotes steam to form, and does not produce turbulent flow or the bubble that promotes to carry secretly impurity.After vapor phase was filtered, ammonia steam can further import the aqueous cleaning device.This aqueous cleaning device designs especially so that small bubbles to be provided, succeeded by the passage by saturated water-bath.This passage provide time enough be used for any particle in the bubble contact and shift with walls liquid, aqueous in.In addition, produce minimum turbulent flow like this, prevent to carry secretly once more impurity.The ammonia steam of being collected by washer can mix the ultra-high purity solution of ammonium hydroxide that is suitable for semi-conductor industry to form with ultra-high purity water.If the ammonia based on anhydrous ammonia is the product of expectation, purified ammonia so for this purpose can filter the back in vapour phase and collect.

This method can be implemented in large-scale self contained facility, but or scale down so that ammonium hydroxide or the ammonia of making to be provided on the spot.

Objects and advantages of the present invention will be by the following detailed description and accompanying drawings and are further understood.

Description of drawings

Fig. 1 is a synoptic diagram of the present invention.

Fig. 2 is the sectional view of the bubbler that uses of the present invention.

Embodiment

The present invention is tripping device or the system 10 that is suitable for making ultra-high purity ammonia.This system comprises the first and second liquid filters/separator 12 and 14 that is connected to vaporizer 18.These parts are made by the material that does not hinder this method most possibly, are generally stainless steel, politef or teflon lined.

More especially, providing liquefied ammonia can be the canned truck of ammonia or the Portable pot that is used for the ammonia of smaller size smaller needs to the ammonia jar 34 of device 10.Ammonia imports import 38 and via pipeline 40 to first liquid separation prefilters 12.By first separator 12, ammonia imports liquid/liquid coalescer 14 via pipeline 42.

Preferred prefilter 12 is a polypropylene filter, and it removes the solid that can destroy the ammonia oil emulsion.This is 1-10 micron filter (preferred 10), has the 15psid peak pressure and falls.Liquid/liquid coalescer 14 is designed to 8-10ppm import and 1-2ppm outlet (free oil).This coalescer can be the horizontal coalescer with two stages.Starting stage will gather into littler oil droplet by the polypropylene filter element to drip.Design is the capillary emulsion that has 0.5-40dyne/cm in order to use like this.In subordinate phase, drop in the negative area more greatly and be separated by continuous ammonia.Pressure by coalescer 14 falls and should be 0-10psid, preferred 0-15psid.Remove via vent pipe 44 and 46 respectively with other impurity at strainer 12 and separator 14 isolating oil.

Liquid phase ammonia feeds vaporizer 18 by coalescer 14.Vaporizer 18 only is the jar with heat exchanger, for example is positioned at the water jacket 50 of base of evaporator.Ammonia enters vaporizer via liquefied ammonia import 52, and this import 52 imports ammonia under the liquid level.Vaporizer also has ammonia vapour outlet 54.

As shown in drawings, jar 18 tilts to vent pipe 58, and this vent pipe is allowed the denseer component discharge of the liquid in the vaporizer 18.Import 52 is the conduit with sensing vent pipe 58 of bending 53.The ammonia of coming in flows to vent pipe 58.Denseer component is an oil or with the ammonia oil emulsion of metallic particles.Denseer component is expelled to the valve 60 that points to emission intensity jar 64 via vent pipe 58.Valve 60 interimly imports pump 72 with liquid via pipeline 70, and this pump makes ammonia be back to import 38 via pipeline 74.This is used in cyclic part liquid in the vaporizer 18.

Outlet 54 is pointed to first and second vapour phase strainer 78 and 82 that comprises vent pipe 84 and 86 respectively by vaporizer 18.Strainer 78 and 82 is 0.05 micron strainer that applies to 0.02 micron-sized Teflon , and peak pressure is reduced to 15psid.Ammonia steam enters valve 81 by strainer 82.Valve 81 can import steam outlet 83 or is connected to the manifold valves 88 of bubble tower 94 bottoms 92 by conduit 90.Collect the steam that imports outlet 83, further as anhydrous ammonia.

When ammonia steam guiding catheter 90, it imports via import 98 via the bottom by bubble tower, and is passed through by spray plate 100, forms the ammonia bubble at this spray plate place and also distributes through this tower reposefully.These bubbles via water 93 from tower 94 upper reaches, then to headspace 101 to vapour outlet 102.

Bubble tower 94 special designs are to produce small bubbles.The length of tower also through design so that so the bubble that produces will stop the sufficiently long time in liquid, move by being transferred to walls in the bubble via Stokes and Brownian to allow any particle in the bubble.Therefore, the length of tower will depend on that bubble size and bubble pass through the speed of liquid in the tower.In order to promote purifying, bubble size should be very little, and should control the speed that ammonia steam imports.

Solid Teflon  spray plate 100 has aperture 108 as much as possible.With the tower with about 10 feet liquid depths and 4 feet vapour spaces is example, and the diameter in hole 108 should be not more than about 3/64 " so that for about 42lbs/hr-ft ²The air-flow of=lbs/hr.ft, separable any impurity enters the liquid in the tower.

Vapour outlet 102 is connected to the 3rd and the 4th vapor filter 104 and 106.These strainers are preferably 0.2 micron order, and peak pressure is reduced to 15psi.Strainer 106 imports collection device with ammonia or can combine and form the mixing device of ammonium hydroxide with high purity water.

According to this method, ammonia is introduced import 38 by jar 34 in envrionment temperature, and by strainer 12 and liquid/liquid coalescer 14, lowers oil-contg extremely less than about 1-2ppm.The metallic particles of carrying secretly in the liquid oils also will be removed.Collected impurity is discharged via vent pipe 44 and 46.

Pressure makes residual liquefied ammonia 52 inflow evaporators 18 by the road.Well heater such as water jacket 50 keeps the temperature of ammonia enough high, producing steam ammonia, but can not height to making ammonia ebullient temperature.The temperature of the water of heating should not be higher than about 55-65 ℃.The water of heating is conducted to water jacket 50 via pipeline 112 and discharges via pipeline 114.Even the static operation of vaporizer is the stirring minimum of liquefied ammonia.In addition, the vapour space that is higher than liquid level in the vaporizer makes that the formation speed of steam is lower.Common maximum velocity of steam is 0.5-1.0fps.Preferred its is lower than 0.1fps, and most preferably is lower than 0.02fps, and this more guarantees in steam not entrained liquids.This prevent liquefied ammonia and any carry secretly impurity by escaping in the steam.

Because jar 18 tilts, denseer impurity will be collected at vent pipe 58.Collected impurity is imported into emission intensity jar 64.

Cross vapor filter 78 and 82 at the vapour stream that the headspace 118 of vaporizer 18 forms.The preferably about 100-125psig of the pressure of headspace 118.First vapor filter 78 is designed to remove and is of a size of about 0.1 micron particle.It is about 0.05 micron impurity that second vapor filter 82 is designed to remove granularity again.If desired, steam can import outlet 83 and collection by valve 81.

Perhaps, steam can import manifold valves 88 by valve 81, and these manifold valves enter airflow diversion the pipeline 90 of the bottom 92 that feeds bubble tower 94.Enter the preferably about 50-60psig of tower 94 gaseous tensions.

Bubble tower is full of saturated high-purity hydrogen ammonium oxide.Ammonia flow is crossed hole in the spray tower 100, forms the bubble that produces via solution of ammonium hydroxide.

It is about 20 to about 30 ℃ that heat exchanger such as water jacket 120 keep the temperature of ammonium hydroxide in the tower.Bubble produces via ammonium hydroxide, and ammonia steam flows through port one 02 by bubble tower.Bubble is to prevent the rate transitions of entrained liquids aqua ammonia and impurity.Ammonia steam is flow through by tower 94 that to remove granularity be 0.2 micron particulate the 3rd and the 4th vapor filter 104 and 106.

Ammonia steam will mix with high purity water now to form ammonium hydroxide.Perhaps it can be collected to be used as gas or anhydrous liq.This ammonium hydroxide is suitable for making unicircuit.Usually, it will have the metallic particles that is no more than 100ppt, and preferably still less.

Thus by utilizing the present invention, form extremely pure ammonia and the problem that do not have the prior art separating device to be run into.Particularly, carrying secretly of impurity minimized by removing the most impurity in the liquid phase before evaporating.In addition, opposite with the turbulent flow vaporizer, make again by using the immobilized vaporizer that carrying secretly of impurity minimizes in the vapour phase.This allows being further purified of use vapor filter.At last, bubble tower is designed to make carrying secretly of impurity to minimize, and provides competent disengaging time to assemble and keep any impurity of carrying secretly to allow by the liquid phase in the bubble tower simultaneously.

Here describe the present invention and implemented the preferred method of the present invention.Yet the present invention itself is only limited by appended claim.

Claims

1. vaporizer (18) that is suitable for purifying ammonia, it comprises the long strip shape jar with bottom surface, first end of the jar of this inclination is lower than the second described jar end, be arranged in described jar first end vent pipe (58) and be used for well heater (50) adapter at described jar of heating ammonia.